Gas pressure-regulating device for dispensing working fluid

ABSTRACT

A system for providing gas to a container includes a source of gas under pressure, a container, and a pressure regulating device. The pressure-regulating device includes an inlet intended to be connected to a source of the gas under pressure, an outlet, connected by a duct to the inlet and intended to be placed in communication with the container, a first valve for limiting the pressure at the outlet to a predetermined maximum value Ps, which valve is a delivery valve placed in a first passage which connects the duct to an orifice for discharging inert gas. The device also includes a second valve for keeping the pressure at the outlet above a predetermined minimum value Pi, which valve is an intake valve placed in a second passage which connects the duct to an orifice that lets fluid into this duct.

This application is a continuation of application Ser. No. 09/354,575,filed Jul. 16, 1999, now U.S. Pat. No. 6,209,568, which is incorporatedby reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pressure-regulating device forsupplying a gas to a container, comprising an inlet intended to beconnected to a source of the said gas under pressure, an outlet,connected by a duct to the said inlet and intended to be placed incommunication with the container, a first valve for limiting thepressure at the said outlet to a predetermined maximum value Ps, whichvalve is a delivery valve placed in a first passage which connects thesaid duct to an orifice for discharging inert gas.

The invention applies in particular to the supply of working liquids inthe electronics industry.

2. Description of the Related Art

The electronics industry, particularly the microelectronics industry,involves the use of ultrapure working liquids such as H₂O₂, HCl, H₂S,etc., for example.

Such liquids are generally held in storage containers, the structure ofwhich makes it possible to prevent these liquids from becomingcontaminated, especially through the presence of particularly expensiveand delicate internal coatings, for example perfluoroalkoxy coatings(PFA).

The delicate nature of these internal coatings considerably limits,inside these containers, the permissible variations in pressure aboutatmospheric pressure to which these containers are subjected externally.

Thus, the gauge pressure inside these containers must, for example, bebetween −20 and +150 mbars.

In order to observe this constraint and avoid the contamination of theworking liquids that are to be dispensed, the vacuum created in such acontainer when working liquid is drawn off is filled by the supply ofcorresponding amounts of an ultrapure inert gas, typically nitrogen.

Nitrogen is generally supplied to a container for the storage of workingliquid by a supply system which comprises a pressure-regulating device,means of connecting an inlet of the device to a source of inert gasunder pressure, these means being equipped with means of expanding thegas to a datum pressure Pc that lies in the range of pressures which arepermissible inside the container, and a pipe for placing an outlet ofthe device in communication with the storage container. Thepressure-regulating device is intended to prevent damage to the storagecontainer in the event of an operating incident.

Until now, there have been two types of pressure-regulating device.

In the first type, the device comprises a permanent communication withthe ambient atmosphere of the duct connecting the inlet and the outletof the regulating device, through a calibrated vent. Although this typeof device provides the storage containers with good protection againstvariations in internal gauge pressure, it does, however, entail constantconsumption of ultrapure nitrogen, whether or not working liquid isbeing dispensed, and this leads to high running costs.

In the second type, the pressure-regulating device comprises a deliveryvalve with a valve element balanced by a spring, to place the duct ofthe regulating device in communication with the ambient atmosphere. Adevice of this kind exhibits numerous drawbacks. Specifically, it doesnot safeguard the containers, on the one hand, against any depressionand, on the other hand, in case of substantial overpressure upstream ofthe regulating device, because of the low delivery rates allowed bythese clack-type valves. Furthermore, this type of device entailsregular checks on the settings of the clack valve and of the expansionmeans, which are dependent on one another. Finally, as the use of metalcomponents in such regulating devices is forbidden in order to maintainthe purity of the inert gases, this type of device is complex andexpensive to produce.

The object of the invention is to solve these problems by providing asimple pressure-regulating device of low manufacturing and running costsand which is able to safeguard storage containers when dispensingultrapure working liquids.

SUMMARY OF THE INVENTION

To this end, the subject of the invention is a pressure-regulatingdevice for supplying a gas to a container, comprising an inlet intendedto be connected to a source of the said gas under pressure, an outlet,connected by a duct to the said inlet and intended to be placed incommunication with the container, a first valve for limiting thepressure at the said outlet to a predetermined maximum value Ps, whichvalve is a delivery valve placed in a first passage which connects thesaid duct to an orifice for discharging inert gas, characterized in thatthe device also comprises a second valve for keeping the pressure at thesaid outlet above a predetermined minimum value Pi, which valve is anintake valve placed in a second passage which connects the said duct toan orifice that lets fluid into this duct.

According to particular embodiments, the device may have one or more ofthe following features, taken in isolation or in any technicallyfeasible combination:

the first valve comprises a first shutter which can move between a lowershut-off position and an upper flow, position, under the action of apositive difference P⁺between the pressures in part of the duct and atthe said discharge orifice, acting against the action of the self weightof the first shutter, the said shutter being of a mass carefullydetermined to balance the action of a predetermined pressure differenceP⁺c;

the first shutter is placed on a seat intended to be substantiallyhorizontal;

the discharge orifice is an orifice for communicating with the ambientatmosphere at pressure Pa, and P⁺c=Ps−Pa;

the second valve comprises a second shutter which can move between alower shut-off position and an upper flow position under the action of anegative difference P⁻between the pressures in part of the duct and atthe intake orifice, acting against the action of the self weight of thesecond shutter, the shutter being of a mass carefully determined tobalance the action of a predetermined negative pressure difference P⁻c;

the second shutter is placed on a seat intended to be substantiallyhorizontal;

the intake orifice is an orifice for communicating with the ambientatmosphere at pressure Pa, and P⁻c=Pi−Pa.

Another subject of the invention is a system for supplying inert gas toa container, comprising a pressure-regulating device, means ofconnecting an inlet of the device to a source of the gas under pressure,and a pipe for placing an outlet of the device in communication with thecontainer, characterized in that the pressure-regulating device is adevice as defined hereinabove.

In an alternative form, the connecting means comprise means of expandingthe inert gas to a datum pressure Pc which lies approximately between Piand Ps, and preferably close to Ps.

A final subject of the invention is an installation for dispensing aworking liquid, comprising a container for storing the working liquid,means of dispensing the working liquid which are connected to thecontainer, a system for supplying gas, especially inert gas, to thecontainer (4), and a source of the gas under pressure, the supply systembeing connected to the source and to the container so as to fill in thelatter a vacuum produced as a result of the withdrawing of the liquid,characterized in that the gas-supply system is a system as definedhereinabove.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING

The invention will be better understood from reading the descriptionwhich will follow, given merely by way of example and made withreference to the appended drawings, in which:

FIG. 1 is a diagrammatic side view in part section of an installationfor dispensing working liquid according to the invention, and

FIGS. 2 to 4 are sectioned and enlarged side views of thepressure-regulating device of the installation of FIG. 1, eachillustrating the operation of this regulating device under differentconditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 depicts an installation 1 for dispensing an ultrapure workingliquid 2 to a consumer unit 3 of an industrial site, for example amicroelectronics site.

This installation 1 essentially comprises a container 4 for storing theliquid 2, means 5 for dispensing the liquid 2, a system 6 for deliveringinert gas to the container 4 and a source 7 of gaseous ultrapurenitrogen at 10 bar absolute.

The container 4 is internally coated with a layer of PFA (not depicted)which means that the gauge pressure inside this container 4 must liebetween −20 mbar and +150 mbar.

The dispensing means 5 comprise a pipe 8 immersed in the liquid 2contained in the container 4 and equipped with a pump 9 placed betweentwo manual shut-off valves 11.

The system 6 for supplying ultrapure nitrogen essentially comprises apressure-regulating device 12, means 13 of connecting an inlet 14 of thedevice 12 to the source 7, and a pipe 15 for placing an outlet 16 of thedevice 12 in communication with the upper part of the container 4.

The connecting means 13 comprise, in succession, in the direction inwhich the nitrogen flows, an expansion valve 170 and a stop andnon-return valve 17.

The pump 9 is rated to be able to supply an appropriate maximum flowrate of working liquid 2.

The expansion valve 170 is rated and adjusted to expand the nitrogenfrom the source 7 as far as a datum pressure Pc corresponding to a gaugepressure of close to 40 mbar, and to supply a sufficient flow rate ofnitrogen to compensate for the flow rate of the pump 9 irrespective ofits speed.

The pressure-regulating device 12 comprises (FIG. 2) a firstsubstantially parallelepipedal external box 18 placed with its lower 19and upper 20 faces substantially horizontal.

The inlet 14 and the outlet 16 of the device 12 are calibrated orificesof appropriate cross section, each formed facing the other in lowerparts of opposite side faces 22 and 23 of the box 18.

The device 12 also comprises walls placed inside the box 18. These wallsform, on the one hand, a second substantially parallelepipedal box 24,one side face of which is formed by part of the wall 23 of the first box18, and the other faces of which are placed some distance away from andsubstantially parallel to the other faces of the box 18. The walls form,on the other hand, a third substantially parallelepipedal box 25,smaller in size than the second box 24. The lower face of this third boxis formed by part of the upper face 26 of the second box 24, and itsother faces are arranged some distance away from and substantiallyparallel to the corresponding faces of the first box 18.

The side face 23 of the first box 18 is also pierced, in an upper part,with a calibrated orifice 27 of appropriate cross section, placing theinside of the second box 24 in communication with the ambientatmosphere.

The lower face 28 of the second box 24 is pierced with a calibratedorifice 29 placing the inside of the second box 24 in communication withthe rest of the first box 18.

The upper face 26 of the second box 24 is pierced with a calibratedorifice 30 placing the inside of the third box 25 in communication withthe inside of the second box 24.

The lower faces 19 of the box 18 and 28 of the box 24 delimit betweenthem a duct 31 connecting the inlet 14 to the outlet 16 of the device12.

Side faces of the third box 25 are pierced with orifices 32 placing theinside of the third box 25, and therefore the inside of the second box24 via the orifice 30, in communication with the rest of the inside ofthe first box 18.

The three boxes 18, 24 and 25 delimit, on the one hand, a first passage34 connecting the orifice 27 to the duct 31 via the orifice 29 and, onthe other hand, a second passage 35, delimited in part between the sideface 22 of the second box 24 and the adjacent side face of the first box18, which connects the orifice 30 to the duct 31 via orifices 32 piercedin the side faces of the third box 35.

The first passage 34 is equipped with a clack-type delivery valve 36,that is to say a valve with a shutter that can move substantially atright-angles to the seat. The seat consists of the lower face 28 of thesecond box 24, and the shutter, that is to say the clack-valve element,is a substantially parallelepipedal block 34 capable of moving in thebox 24. This block 37 is of carefully determined mass and is placed onthe face 28.

The mass of the block 37 is carefully determined to balance the actionthereon of a gauge pressure P⁺c of about 40 mbar (corresponding to amaximum absolute pressure Ps) at the orifice 29 of the duct 31.

The block 37 is guided by the side walls of the box 24 and can movevertically between a lower position in which it shuts off the orifice 29(FIG. 2), in which position the block 37 rests on the face 28, and anupper position in which there is flow through the orifice 29 (FIG. 3),in which position the block 37 is raised off the face 28.

The second passage 35 is equipped with a clack-type intake valve 39, theseat of which consists of part of the upper face 26 of the second box 24and the shutter, that is to say the clack-type valve element, of whichis a substantially rectangular plate 41 able to move in the third box25. This plate 41 is of carefully determined mass and placed on the face26.

The mass of the plate 41 is carefully determined to balance the actionthereon of a gauge pressure P⁻c of about −5 mbar (corresponding to aminimum absolute pressure Pi) in part of the duct 31.

This plate 41 is guided by the side walls of the box 25 and can movevertically between a lower position in which it shuts off the orifice 30(FIG. 2), in which position the plate 41 rests on the face 26, and anupper position for flow through the orifice 30, in which position theplate 41 is raised off the face 26 of the second box 24 (FIG. 4).

The pressure-regulating device 12 is made of plastic such aspolypropylene and/or polyethylene.

The dispensing means 5 allow liquid 2 to be pumped from the container 4to be dispensed to the consumer installation 3. The supply system 6allows ultrapure nitrogen to be supplied to the container 4 to fill thevacuum created therein as a result of the dispensing of the liquid 2.

FIG. 2 illustrates the way in which the pressure-regulating device 12operates when the gauge pressure at the inlet 14, the outlet 16 andtherefore in the container 4 is between P⁻c and P⁺c.

The shutters 37 and 41 are in the shut-off position and thus form analmost perfect seal between the inlet 14 and the outlet 16. Only anitrogen leakage flow rate, depicted by the arrow 43, flows through theorifice 29 between the walls of the box 24 and the block 37, and thusmakes it possible to prevent any vapour of the liquid 2 from returningtowards the expansion means 170 when the pump 9 is not running.

FIG. 3 illustrates the way in which the device 12 operates when thepressure at the inlet 14 is above P⁺c, for example in the event ofdefective operation of the expansion means 170.

The shutter 37 is then in the raised, flow, position, and the shutter 41is in the shut-off position. The overpressure with respect to P⁺c at theinlet 14 of the device 12 is then discharged, via the first conduit 34,to the ambient atmosphere, as depicted diagrammatically by the arrow 44.The pressure at the outlet 16, and therefore inside the container 4, isthus kept below its maximum permissible value, even when the pressure atthe inlet 14 is 10 bar absolute, because of the delivery through theorifice 27.

FIG. 4 illustrates the operation of the device 12 when the gaugepressure in part of the duct 31 is below P⁻c, for example when the flowrate of nitrogen supplied by the device 12 is not high enough tocompensate for the flow rate at which liquid 2 is drawn off. The shutter37 is then in the shut-off position and the shutter 41 is then in theraised, flow, position. Air is therefore taken in from the ambientatmosphere towards the outlet 16 and therefore towards the container 4via the second passage 35, as depicted diagrammatically by the arrow 45.Thus, the pressure inside the container 4 remains above its minimumpermissible value even with zero pressure at the inlet 14. The liquid 2therefore becomes contaminated, but the integrity of the container ispreserved.

The pressure-regulating device 12 according to the invention thereforemakes it possible, in complete safety, to supply inert gas to a storagecontainer 4 of an installation 1 for supplying working liquid. Theconsumption of nitrogen, or more generally of inert gas, is, inpractice, minimal and automatically tailored to the speed of the pump 9.

Furthermore, the particularly simple structure of this device means thatit can be made entirely out of materials which are well suited topreserving the purity of the inert gas used and of the working liquidsdispensed.

Finally, this device has no adjustment controls, which makes it simpleto use, and the limited number of moving parts means that it sufferspractically no wear over time.

What is claimed is:
 1. A pressure-regulating device useful for supplying a gas to a container, comprising: an inlet for placement in fluid communication with a source of the gas under pressure; an outlet for placement in fluid communication with the container; a duct connecting the outlet to the inlet for placement in fluid communication with the container; an orifice for discharging fluid from the device and permitting fluid to enter the device; a first passage fluidly connecting the duct with the orifice; a second passage fluidly connecting the duct with the orifice; a first valve limiting the pressure at the outlet to a predetermined maximum value Ps when the inlet is fluidly connected to a source of gas under pressure, the first valve being a delivery valve placed in the first passage; and a second valve maintaining the pressure at the outlet above a predetermined minimum value Pi when the outlet is fluidly connected to a container, the second valve being an intake valve placed in the second passage; wherein the first valve is configured with an almost perfect seal to permit a leak flow past the first valve to assist in preventing backflow from the outlet from passing out the inlet.
 2. The device according to claim 1, wherein the first valve comprises a first shutter having a weight and which can move between a lower shut-off position and an upper flow position, under the action of a positive difference P⁺ between the pressures in part of the duct and at the discharge orifice, acting against the action of the first shutter, the first shutter being of a mass selected to balance the action of a predetermined pressure difference P⁺c.
 3. The device according to claim 2, wherein the first shutter is positioned on a seat intended to be substantially horizontal.
 4. The device according to claim 2, wherein the discharge orifice is an orifice communicating with the ambient atmosphere at pressure Pa, and in that P⁺c=Ps−Pa.
 5. The device according to claim 1, wherein the second valve comprises a second shutter having a weight and which can move between a lower shut-off position and an upper flow position under the action of a negative difference P⁻ between the pressures in part of the duct and at the intake orifice, acting against the action of the second shutter, the second shutter being of a mass selected to balance the action of a predetermined negative pressure difference P⁻c.
 6. The device according to claim 5, wherein the second shutter is positioned on a seat intended to be substantially horizontal.
 7. The device of claim 5, wherein the intake orifice is an orifice communicating with the ambient atmosphere at pressure Pa, and in that P⁻c=Pi−Pa.
 8. The device of claim 1, further comprising means for connecting the inlet of the pressure-regulating device to the source of gas under pressure, and a pipe for placing the outlet of the pressure-regulating device in communication with the container.
 9. The device of claim 8, wherein the connecting means comprises a means for expanding a gas to a datum pressure Pc which lies approximately between Pi and Ps disposed in the connecting means between the inlet of the pressure-regulating device and the source of gas under pressure.
 10. A pressure-regulating device useful for supplying a gas to a container, comprising: an inlet for placement in fluid communication with a source of the gas under pressure; an outlet for placement in fluid communication with the container; a duct connecting the outlet to the inlet for placement in fluid communication with the container; an orifice for discharging fluid from the device and permitting fluid to enter the device; a first passage fluidly connecting the duct with the orifice; a second passage fluidly connecting the duct with the orifice; a first valve limiting the pressure at the outlet to a predetermined maximum value Ps when the inlet is fluidly connected to a source of gas under pressure, the first valve being a delivery valve placed in the first passage; and a second valve maintaining the pressure at the outlet above a predetermined minimum value Pi when the outlet is fluidly connected to a container, the second valve being an intake valve placed in the second passage; wherein the first valve, the second valve, or both comprises a free floating block and a valve face including a valve orifice.
 11. The device according to claim 10, wherein the first valve comprises a first shutter having a weight and which can move between a lower shut-off position and an upper flow position, under the action of a positive difference P⁺ between the pressures in part of the duct and at the discharge orifice, acting against the action of the first shutter, the first shutter being of a mass selected to balance the action of a predetermined pressure difference P⁺c.
 12. The device according to claim 11, wherein the first shutter is positioned on a seat intended to be substantially horizontal.
 13. The device according to claim 11, wherein the discharge orifice is an orifice communicating with the ambient atmosphere at pressure Pa, and in that P⁺c=Ps−Pa.
 14. The device according to claim 10, wherein the second valve comprises a second shutter having a weight and which can move between a lower shut-off position and an upper flow position under the action of a negative difference P⁻ between the pressures in part of the duct and at the intake orifice, acting against the action of the second shutter, the second shutter being of a mass selected to balance the action of a predetermined negative pressure difference P⁻c.
 15. The device according to claim 14, wherein the second shutter is positioned on a seat intended to be substantially horizontal.
 16. The device of claim 14, wherein the intake orifice is an orifice communicating with the ambient atmosphere at pressure Pa, and in that P⁻c=Pi−Pa.
 17. The device of claim 10, further comprising means for connecting the inlet of the pressure-regulating device to the source of gas under pressure, and a pipe for placing the outlet of the pressure-regulating device in communication with the container.
 18. The device of claim 17, wherein the connecting means comprises a means for expanding a gas to a datum pressure Pc which lies approximately between Pi and Ps disposed in the connecting means between the inlet of the pressure-regulating device and the source of gas under pressure. 